Introduction:A synergistic antibiotic combination of a penicillin and gentamicin (AG) is recommended first line management of Enterococcus faecalis infective endocarditis (EFIE). We compare the treatment outcomes between the conventional AG regimen to those treated with a combination of penicillin and ceftriaxone (AC). Given reported beta lactam toxicity risks, we also examine the difference in treatment outcomes between regimens of low dose, 1g 12 hourly (ACL) and high dose ceftriaxone, 2g 12 hourly (ACN) in combination with penicillin.Methods:A retrospective cohort study of patients treated for EFIE at single tertiary centre (2012–2019). Outcome measures examined are 90 & 180-day mortality, treatment associated adverse events, and relapse of bacteremia (within 1 year).Results:39 patients were enrolled [59% given (AC) (n = 24), 24% received ACL (n = 10) and 34% received ACN (n = 14)]. 39% received AG (n = 15). We found no significant difference in the mortality outcomes at 90 and 180 days between: a) those treated with a gentamicin combination and ceftriaxone combination overall (P = .114, P = .061) and b) between high and low dose ceftriaxone (P = 1.0, P = .673). No significant difference was noted between the above groups in incidence of relapsed bacteremia (P = .662, P = .414). A greater number of adverse events was observed in the gentamicin group compared to the overall ceftriaxone group (P = .009), with no difference between the high and low dose ceftriaxone groups (P = .05).Conclusion:Combination treatment with penicillin/ceftriaxone appears to be as effective (using low and high dose ceftriaxone) as penicillin/gentamicin in EFIE, with a lower rate of adverse events.

Introduction A synergistic antibiotic combination of a penicillin and gentamicin (AG) or ceftriaxone (AC) is used in the management of Enterococcus faecalis infective endocarditis (EFIE). We compare the treatment outcomes between AG and AC, including low and high dose ceftriaxone (1 and 2 g 12 hourly). Methods A retrospective cohort study of patients treated for EFIE at single tertiary centre (2012–2019). Outcome measures examined were 90- and 180-day mortality, treatment associated adverse events and relapse of bacteraemia (within 1 year). Results 39 patients were enrolled [61.6% given (AC) (n = 24), 24% received ACL (n = 10) and 34% received ACN (n = 14)], 38.4% received AG (n = 15). We noted a difference in the mortality outcomes at 90 and 180 days between those treated with AG and AC overall (6.7% and 33.3%, respectively) although this did not reach statistical significance (P = 0.114, P = 0.061). No significant difference was noted between these groups in incidence of relapsed bacteraemia with two cases noted in the AC cohort (8.3%, 2/24) and none observed (0/15) in the AG cohort (P = 0.662, P = 0.414). A greater number of adverse events was observed in the AG group (11/15, 73.3%) compared to the overall AC group (6/24, 25.0%) (P = 0.009), with no difference between the high and low dose ceftriaxone groups (P = 0.05). Conclusion Combination treatment of EFIE with AC is associated with a reduced number of adverse events in comparison to AG groups. Although increased mortality was observed in the AC group, this did not reach statistical significance, and reflects the greater comorbidities and reduced capacity for surgical source control in this cohort.